Cold Purpose
by risingsunsets
Summary: The Evans' had more than one magical child. Petunia Evans is just as gifted as her sister, and perhaps a shade more ferocious. A Slytherin, she becomes one of the Order's better fighters, and when her sister dies, buries her grief to raise Harry Potter, son of a boy she never cared for and a sister she loved very much. One-shot, will write more if there's interest.


An intro: I've always held interest in the stories where Petunia is actually a decent person, and takes care of Harry. Recently I found a picture on DA - art/petunia-90865435- (remove the two spaces between the slashes and the g) that shows what might have happened if Petunia was a witch, too. So this whole story is inspired by that. Kind of. Loosely.

For the sake of the story, I've changed their birth dates so that they could be in Hogwarts at the same time in the same year.

* * *

"Mummy told us not to!"

"But Tuney, it isn't hurting anyone, and there's no one else here!"

Lily picked up the flower, and began to move the petals without touching them, curling around like an octopus' legs. Petunia, despite her admonishment, looked interestedly at the moving petals. "Why can't I do anything like that?" she said enviously. "It was only the time Charlie Erikson pulled my hair and his hand puffed up..."

"And the time Mum tried to cut your hair and the scissors fell apart!"

Petunia grinned, but her discomfort with the whole idea returned a little, and she asked a little worriedly to Lily, "How do we do it? What if there's something wrong with us?"

At that moment, a dirty-looking boy stepped out from a nearby tree. "It's obvious, isn't it?"Lily shrieked, and Petunia turned around, white-faced, both afraid. The flower floated to the ground, forgotten.

"What's obvious?" asked Lily.

"You're witches!"

At this, Petunia spoke, a little angry despite her fear. "We're not witches! What a mean thing to say to someone!"

The boy flushed, shaking dark hair frantically. "I didn't mean... I meant you're _real_ witches! I know, cause my mum's one. And I'm a wizard! I haven't met anyone else like me..."

Petunia snorted, and grabbed Lily's hand. "Well prove it then, because I don't think so. _I_ think you're just a dirty boy who's been spying on us!"

"Wasn't spying" the boy mumbled, but he moved his hand anyway, and suddenly, something began moving a lock of Lily's hair.

She yelped and moved away, startled. "That wasn't nice!"

He looked a little sorry, but moved closer. "We can't control it all the time though! They only teach us that at Hogwarts."

"What's Hogwarts?"

"It's a school! It's a whole school for people like us to learn magic!"

* * *

"Can you tell us about the Dementors, Sev?"

"Why do you want to know about them awful things for?" He asked.

"Well they run the prison, and you said it's illegal for us to do magic outside of school.."

"They wouldn't arrest us for that! We haven't even got wands yet, it's just accidental to them. But once we get our wands, we have to be careful."

They all were laying in a little meadow close to the park, Lily in the middle, Severus and Petunia off on either side.

"Are your parents still fighting, Sev?"

"They're always fighting. But soon enough our letters will come and we'll be gone. It doesn't matter."

Lily smiled and sat up. "When do we get our letters?"

Severus frowned a little. "I don't know for sure, it's in the summer, and you have to be eleven.

Tuney frowned. "But I've already been eleven!"

"No, it has to be before the school year in September. When did you turn eleven?"

"October."

"Oh. You just missed it last year, then. Anyway, you won't get just the letter. You're both muggleborns, so someone from the school will come to explain everything."

"Does it make a difference, us being muggleborns?"

Lily looked anxious, and Tuney looked calculating, and Severus hesitated as he looked at them both. "No, it doesn't make any difference."

"Good," said Lily, closing brilliant green eyes. "I was wondering."

Petunia did not look as convinced, still staring at him questioningly with her own hazel eyes.

* * *

"Tuney, come on, we're going to miss the train!"

Bright red hair bounced on the platform, rushing through the little crowds of people. Petunia was more cautious, approaching the train with their parents, Severus a little ways ahead.

As they reached the platform, Mrs. Evans gathered them all around her. "You girls be good, okay? Make sure you write to us, and don't cause any trouble."

Lily managed a solemn "Yes, Mum" despite her excitement, and Petunia nodded. Now that the train was here, that it was real, that they were leaving, she found herself a little scared. What if Hogwarts wasn't everything they wanted it to be?

"Thank you for driving me, Mr. Evans." said Severus politely, and was rewarded with a smile. "It was no problem, Severus. I don't know what we would have done if the girls hadn't ran into you. Even with the professor explaining everything, it's hard to wrap our heads around a world so different. You've been invaluable."

Severus didn't quite know what to say, and let himself be swept into the hug Mrs. Evans gave them all.

They loaded their trunks onto the train, and after saying their goodbyes to the girls' parents, found a compartment to sit in. Lily almost immediately flopped on the seat and let out a high pitched giggle. "We're going to learn about magic!"

It was enough to break Petunia out of her melancholy, and she smiled too. "It's going to be so interesting, I already know it," she said, willing herself to relax. "All of the things in the books..."

"You both had better be in Slytherin with me," said Severus, just as the door opened and two other boys walked in.

"Slytherin? I think I'd leave, wouldn't you?" One of the boys said this to the other, but the other didn't smile.

"My whole family has been in Slytherin," said the second boy, and the first mocked outrage. "Blimey, and I thought you seemed alright!" The second laughed at that.

"Well, where are _you_ planning on going, then?" asked Petunia, a little miffed that these boys had invaded their compartment just to be rude.

"Gryffindor, where dwell the brave at heart! Like my dad."

Severus snorted, and the boy looked over, narrowed black eyes apparent. "Got a problem with that?"

"No," although his sneer said otherwise. "If you'd rather be brawny than brainy..."

"Where are you planning on going then, seeing as you're neither!" interjected the second boy, and they laughed.

"Wherever it doesn't have you two idiots!" said Petunia, outraged on Severus' behalf, although he hardly need the backup. Lily took both of their hands and marched them out of the compartment, raging about mean boys being everywhere, even in _magical schools_ where everything was supposed to be a fairy tale.

* * *

"Black, Sirius!"

The second boy on the train stepped up to the Hat to be Sorted, and almost as soon as it touched his head, the Hat shouted "GRYFFINDOR!" Petunia frowned at him, and Lily was curious. Severus looked bored.

"Evans, Lily!"

Lily glanced a little worriedly at her sister and Sev, but walked firmly up to the Hat and jammed it on her head.

"GRYFFINDOR!"

Excited, Lily jumped down to join Gryffindor table, and Severus looked worriedly between her and Petunia. She sent them a small smile.

"Evans, Petunia!"

With a little more trepidation than her little sister, Petunia walked to the Hat, and gingerly placed it on her head, and Severus Snape waited...

"SLYTHERIN!"

A small number of students looked interested. It was, after all, a little odd that siblings would come at the same time and be Sorted into a different House. Severus looked supremely relieved, and a little surprised. He thought Tuney and Lily would be together, since they were always together. Petunia took off the hat and walked purposefully to Slytherin table amidst the clapping, sitting next to a larger black-haired student she thought might be a Prefect. Brown eyes swept over her welcomingly, but ultimately uninterested.

When "Potter, James!" was called out, the first boy they met swaggered up to the Hat and dropped it on his head, looking for all the world like he didn't care about the outcome. The Hat shouted "GRYFFINDOR!" after perhaps half a second.

Finally, after many other students, the woman called "Snape, Severus!" and Severus made his way up to the Hat, and as he set it on his head, Lily and Petunia waited. _Finally_ -

"SLYTHERIN!"

Severus took off the Hat and ran to join Petunia at Slytherin table.

* * *

"But I thought we were all supposed to be friends?" Severus asked, as they all walked down the hall. " _Best friends_?"

"We are!" said Lily, a little angrily, "But you're hanging out with Avery, and Mulciber! Mulciber, Sev! Do you know what he did to Mary MacDonald the other day?"

"It was nothing," said Serverus anxiously, "It was just a laugh.."

"That was the Dark Arts, Severus Snape, not just a laugh!" Petunia huffed angrily. "And I would know, I heard them laughing about it in the common room!"

Even after years of being in separate houses, Tuney and Lily were still together, especially in anger. Severus looked between them, upset. "Well what about what Potter and his stupid friends get into?! I know he's messing with stuff too, same as any of them!"

"Potter doesn't have anything to do with this conversation, Sev!" said Petunia, always good at spotting the redirection. Severus stuck to it.

"Well he is! He struts around everywhere, he's always disappearing on the full moon, right when Lupin always looks sick.."

"I know your theory, Sev, and I know James Potter is an arrogant toerag. I don't need you to tell me that. But Mulciber is _evil, Sev,_ evil, and I can't understand why you're around him..."

* * *

"Who wants to see me take off Snivelly's trousers?"

"James Potter, you let him down now! What has Severus ever done to you?!"

"Well, it's more of the fact that he exists, if you know what I mean..."

Lily rounded on him, wand out and ready to hex him, as Petunia came into the courtyard, and Severus, wide-eyed and utterly humiliated, shouted "I don't need any help from filthy mudbloods like them!"

Shocked, Lily turned to face Severus, and narrowed hard green eyes.

"Well alright then, _Snivellus_." she said, forcefully, and Severus' face blanched. She made to walk away, when James called out to her.

"Hey, Evans! Come on a date with me."

"As if I would ever date you, you spineless bully! You're just as bad as he is, picking on everyone you meet and hexing people for the fun of it! You make me _sick_!"

James Potter's black eyes went wide. "I am not! I would never call you a.. a.."

But Lily had already turned around and walked toward the castle, and Petunia wondered how things could have changed so quickly between her, Lily, and Severus...

* * *

"Lily, he's desperate."

"I don't care!"

"Why not? How long has he been our friend? He was scared and humiliated, and he lashed out. He's sorry!"

"Why does that make it any better, Petunia? The first thing he does, when I'm there to get him out, is to lash at me, at us! And worse, with that word! He hasn't listened to us about those other friends of his Tuney, I'm not stupid, and neither are you. You know what's coming, and you know what those people want to do with people like us. He's going to do the same thing!" Lily stopped, and continued again in a wavering voice, "I'm scared for you, Tuney. You're so close to them."

The sisters fell silent, both uncertain and sad.

"It's not so bad in the Slytherin rooms, you know," said Petunia, finally. "Slytherin's not some Dark Lord factory that everyone makes it out to be. James Potter has no idea what he's talking about. Sure, there are the blood purists, and I avoid them, but... most are nice. I have friends. I just hoped... I hoped Sev would have been with me. Would have stuck with me there and avoided them. I don't know why he's in with the.. well, they talk about joining You- Know- Who," she finished, at a whisper. "I just hoped that if we made ourselves open to Sev, that he'd break away eventually.."

Lily nodded, and the sisters hugged.

"I'll be careful Lily, and you be careful too. You know this isn't limited to Slytherin..."

Lily nodded. "I'll be careful."

* * *

"So. What's this I hear about James Potter?"

"I don't know. What's this I hear about Amos Diggory?"

"Amos Diggory hasn't been an awful brute for the last six years."

Lily sighed. "I know, Tuney, but..."

"But he got handsome?" _Well, that was true enough._

"He's stopped, Petunia. He and his friends aren't doing that kind of thing anymore."

Petunia snorted, eyebrow raised over hazel eyes, looking darker than usual. "I'll believe that when I see it. Or.. don't see it, as the case were. Because Se-Snape is still walking into the common room limping, so I don't believe it for a second."

Lily looked supremely unconcerned, and Petunia sighed. "Listen, I'm not going to tell you what to do. Just, be careful. People don't just change."

* * *

She was at their wedding, two years later.

"Hey Petunia, do you know how to work a camera?" She sighed, and hollered over her shoulder, "Sirius Black, if you didn't know how to work a camera, then why did you offer to take the pictures?"

Shoulder length black hair fell into his eyes as he shrugged. "I didn't think it would be that hard to figure out."

Shaking her head and muttering at the colossal idiocy of a pureblood wizard trying to figure out a muggle device with no previous experience (motorbike not withstanding), she went over and pushed him out of the way.

" _Hey_!"

"Go stand in the wedding party, you great buffoon! I'll get the picture." The harshness of the words were negated by Petunia's laugh, and she made to get under the tarp on her side of the camera.

Sirius, sending a dashing smile her way, moved up to snake his arms around James and Lily. The camera flashed as they laughed.

* * *

"Professor Dumbledore, you wanted to see me?"

The normally pleasant mood of the Headmaster was subdued. He was troubled, Petunia realised, and immediately was on alert.

"Yes, Miss Evans. Please walk with me a little."

She nodded, and together began to pace the grounds of Hogwarts, which already seemed so distant to her. She had done exceptionally well in all her classes, of course. Her OWLS and NEWTS had been all Os, except for her A in History of Magic, boring class as it was. Hogwarts had never lost the magic of the new for her, but now, in the middle of the War, it felt like so much longer than a year had passed.

"A little while ago, I received word from one of Voldemort's recruits, a Death Eater. It had to do with a piece of information he delivered to Voldemort, a Prophecy that had to do with his defeat."

Petunia stopped. She had never put much stock into Prophecies, her one year in Divination had left her with no doubt of its unreliability, and she had heard from other friends who ended their term this year that the new teacher was even more scatterbrained and unreliable.

"You... believe in prophecies, Headmaster?"

He smiled at this, sensing her disregard, and turned toward her fully. "As it happens, I hold little care for the subject of Divination. Even true prophecies are not absolute, but conjecture of the Sight that affects people based on probabilities and Arithmany." She nodded.

"However, I believe this one will come to pass, for two reasons. One, it speaks of Voldemort's defeat, and Voldemort is not the kind of man who would let a threat to him slide. Secondly, the prophecy he was delivered is incomplete."

"Sir?"

"I managed to stop the spy listening at the door from hearing everything."

Petunia looked shocked. "You were there?"

Dumbledore nodded. "It was given at a staff interview. But this isn't why I called you here. You are here because of who delivered me the news, and who is in the prophecy in question. It has to do with a babe born at the end of July."

Petunia paled. "Lily's pregnant. She's due in July..."

Dumbledore let out a small sigh. "Yes. It could also apply to Frank and Alice Longbottom"- Petunia gave another frightened look- "But I believe it to be your sister."

"Why Lily?" she asked, voice hardly louder than a whisper, "Why do you think it's her?"

"Because the spy that heard the prophecy, and who later came to me for help, was Severus Snape, and Mr. Snape believes it is about her."

* * *

"Don't kill me!"

"And why should I not?!"

In the dark of Spinner's End, Severus Snape lay cowering under Petunia Evans' wand, wide black eyes shining from the moonlight drifting in from the window, catching his tears.

"I stood up for you, Severus Snape! For years, I gave Lily excuses, for years, I did my best to protect you! Even after you threw it back in our faces, even after you broke Lily's heart with your words, I did my best to see you go unhurt. And this is how you repay me! Now You-Know-Who is after her personally, will kill her because of her babe, and the whole reason for it lays in front of me right now, _well tell me, Severus Bloody Snape, why shouldn't I kill you right now?"_

"I- I didn't know, Petunia, _I didn't know it meant her, I didn't even know she was pregnant_! As soon as I found out, I went to Dumbledore, I've been spying for you all. Every piece of information I have, everything that could even come close to hurting her, I've passed on! I've been doing my best to protect her, I swear it!"

She raised her wand and cursed him with one of his own inventions, and dark liquid started to trickle from a new tear in his robes. Snape doubled over in pain.

"I believe you, you know. I've heard it all from Dumbledore already. But make no mistake, Severus Snape, the only reason I won't kill you now is that Dumbledore, in his all-seeing wisdom" -she said that in a high-pitched voice, almost a shriek- "has seen fit to make YOU part of the Order!"

She kicked him over to face her again, and there was true fear in her former friend's eyes now. "If Lily dies, the fault lies squarely on _you_!"

She turned to leave, but as she got to the door, Snape found his wand.

" _Expecto Patronum_!"

Petunia whirled around- face to face with a silvery white doe, the same as her sisters. Her eyes hardened at the animal -and the man who conjured it- and swept out the door.

* * *

"Petunia."

"Lily?"

"James and I, we know that You-Know-Who's after us. Dumbledore suggested something the other day, the same protecting Headquarters is under. The- the _Fidelius_. Please, I was wondering if you could help us."

"Who else have you asked?"

"We asked Sirius. He said he'd... he'd tell everyone he was the Secret-Keeper, but he's worried, Tuney." Lily's voice dropped, and Petunia had to come closer. "He's too high profile. If he gets k-killed..." She stopped, and Petunia hugged her. "If it happens, we'll be vulnerable. Can you do it, Tuney?"

She wanted to say yes. She wanted to take that weight off her sister, give them some security, but she couldn't.

"Lily, I... I'm not a safe person to use. You know I'm out on missions a lot, but... I'm usually doing a lot of fighting, and I'm muggleborn too." She closed her eyes. "I'll do it if you can't find another person to trust, Lily, but.."

Lily nodded. "One of us is a traitor, Tuney," she whispered. "There's too many attacks hitting too close to home recently. We don't know, but... James and Sirius think it might be Remus." She nodded. It wasn't a new thought, the idea had been whispered among headquarters for the last month. "We're.. going to ask Peter, tell him Sirius will cover, just in case things go wrong... Petunia, I can't let Harry get hurt."

"I know, Lily. I'm going to help you, any way I can."

Lily nodded, still pale, and they heard Harry cry from upstairs. As Lily walked up to grab him, Petunia said, "Don't tell anyone you offered to me, not James, not Sirius, not Peter. Only if Peter declines, alright?"

"Alright."

* * *

The two Death Eaters Petunia fought late Halloween night suddenly screamed out in pain, clutching their forearms. She took the opportunity to bind them in summoned rope, pulling them down, and prevented them from _Apparating_ away.

"What's the matter, can't go to your precious _Lord_?!"

One, gasping in pain, cried out. It was clear he shouldn't have been told anything important, by how quickly he ran his mouth. "It's not a Summoning! It... auuggh, it hurts! It feels like the Dark Lord died! What have you done?"

 _"He's... no, we didn't launch an attack, I would have...no. Lily."_

She Stupefied them both and _Disapparated_...

To a house that was half rubble.

* * *

She stopped, frozen. This couldn't be happening, Lily couldn't be.. and James, and... _Harry. Where was Harry?_

The thought spurned her from her stupor, and she made to run through the part of the house that still stood, when another crack startled her, and she pulled out her wand on whoever it was, ready to fire off any number of the curses she had perfected over the last year, when she saw it was Sirius. He looked no less devastated than she was. Her wand dropped.

"Sirius, you have to help me.. You have to.. Harry has to be in there..."

A baby's wail confirmed her words, and they both ran inside, right into James' body in the living room, glasses askew, his wand nowhere to be seen.

"Where..." began Sirius, choking back tears, but Petunia dragged him up the stairs, into the hallway, and they threw open the nursery door, that opened to half cold night, half room. It contained a little child, screaming for his mother, and... _Lily_ , eyes staring into nothing. Petunia choked back a sob and shakily stepped forward to grab Harry and pull him from the crib, and her eyes were drawn to a large, lightning bolt shaped cut on his forehead.

"Sirius.. We need to get Harry out of here.. what if one of His followers comes by to.. to see..."

Sirius nodded, and they _Disapparated_ to the only place she knew was safe, the Hogwarts gate.

* * *

"This is my fault, this is all my fault.." She heard Sirius say, as they walked up to the gate, pushing it open. "I told them not to use m- Peter." His eyes went wild. "I have to find Peter, I'm going to kill him, I'm going to-"

Whatever he was going to do to Peter Pettigrew was cut off as Petunia smacked him full-force in the mouth.

"You WILL shut your _mouth_ , Sirius Black!" she half yelled, half whispered, afraid of riling Harry up more. "You're an Auror, for Merlin's sake, you will go out and arrest Peter, _and we will watch as they throw him into Azkaban_!"

He looked shocked. "He.. he betrayed us... He doesn't deserve to live..."

Petunia shook her head, turning back to the castle, grief turned to cold purpose. "No. He doesn't deserve to die." She shifted her arms to cradle Harry, who was finally falling asleep, and began walking.

It sent a shiver down Sirius's spine.


End file.
